<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <title>Document</title>
    <style type="text/css">
        .box1{
            width:100px;height:100px;
        }
        .mi{
            width:100px;height:100px;
        }
    </style>
    <script src="jquery/jquery-3.2.1.min.js" type="text/javascript"></script>
</head>
<body>
    <div class="box">
        <ul>
            <li>1</li>
            <li>2</li>
            <li>3</li>
            <li>4</li>
            <li>5</li>
        </ul>
    </div>
    <div class="box1">
    <p>111</p>
    <p class="mi"></p>
    </div>

    <span style="display:none;">222222</span>
    <script>
         // $('.box ul li:even').css("color","red");
         // $('.box1:parent').css("background","green");
         // $('.box1:has(p)').css("background","gray");
         // $('.box1xing :contains(1111)').css("background","yellow");
         $('div:empty').css("background","blue");
         $('span:hidden').show().css("background","red");
         $('div:visible').css("border","1px solid red");
    </script>
</body>
</html>